The role of bile salts in the intestinal radiation syndrome will be delineated so that practical measures to prevent or ameliorate the syndrome can be recommended. Bile acid composition, concentration and turnover will be measured in irradiated rats. Effects of bile salts, bile diversion and irradiation on intestinal transport of nutrients and electrolytes via tranomucosal and shunt pathways will be measured. Electrophysiological studies of voltage clamping, input resistance and cable properties will characterize intestinal mucosal function in irradiated rats and delineated effects of bile salts and bile diversion. These data should support or refute the hypothesis that the intestinal radiation syndrome is a form of cholerheic enteropathy, responsive to treatment. Basic physiologic information will be obtained concerning intestinal cellular function and the role of bile salts.